Direct Petrol Injection
There are manufacturers who have scrapped their 5-valve engines after the arrival of the direct fuel injection. Apparently this seems to require more space in the cylinder head. Now the injector-valve must be also
accommodated - of course almost always in a central position.
Assuming we have two 2 intake ports per cylinder from the right. This engine obviously works continuously with a homogeneous mixture, because there are no flaps causing swirl. The inducted air is directed along
the cylinder wall and diverted past the piston, thus the swirl reaches the spark plug where previously fuel was injected.The above figure shows impressively, particularly in the enlargement, the limited space in the
cylinder head. Very small roller cam followers with an even smaller valve clearance offset provide for camshafts lying
further outside. Between, obviously, two cylinder head covers, an oil-free area remains for the assembly of spark plug and injector. Thereby, the hollow cavities in the cylinder head have been, to a great extent
exhausted. Thus the spark plug opening continues upwards, not straight, but sloping from the centre. This makes the assembly using a socket-wrench, just about possible. Interesting are also the remaining cooling
channels in the cylinder block which are even tapered towards the bottom according to the amount of cooling needed.